Predictability of Residual Postoperative Astigmatism After Implantation of a Toric Intraocular Lens Using Two Different Calculators

Figures & data

Table 1 Demographics

Parameter	Mean ± SD (Range)
Age	71 ± 8.9 (40–89)
Gender	63 Females (57.8%), 46 Males (42.2%)
AL (mm)	23.66 ± 0.85 (20.95–26.14)
Keratometric Astigmatism (D)	1.74 ± 0.38 (1.24–2.86)
IOL Power (D)	20.62 ± 2.50 (16–27)
Postoperative Manifest Refraction Sphere (D) Cylinder (D)	−0.30 ± 0.45 (−1.50–1.00) 0.66 ± 0.52 (0–2.50)

Abbreviations: AL, axial length; D, diopters; IOL, intraocular lens; SD, standard deviation.

Table 2 Residual Astigmatism Prediction Errors (Arithmetic and Centroid) by Method of Calculation (n=109)

	enVista	EVO	p-value
Mean ± SD (D)	0.63 ± 0.43	0.57 ± 0.38	0.10
Range (D)	0.03–2.23	0.03–1.84
Median (D)	0.56	0.51
Centroid ± SD (D)	0.37 ± 0.66 @ 179	0.17 ± 0.67 @ 090	x-component: p < 0.0001 y-component: p = 0.8579

Abbreviations: D, diopters; EVO, Emmetropia Verifying Optical toric IOL formula v2.0; SD, standard deviation.

Figure 1 Residual astigmatism prediction error centroid magnitude by method of calculation.

Abbreviations: ATR, against-the-rule; D, diopters; EVO, Emmetropia Verifying Optical toric IOL formula v2.0; RA, refractive astigmatism; WTR, with-the-rule.

Figure 2 Proportion of eyes with arithmetic residual astigmatism prediction error within 0.5, 0.75, and 1.00 diopters (D).

Abbreviation: EVO, Emmetropia Verifying Optical toric IOL formula v2.0.

Table 3 Residual Astigmatism Prediction Errors by Method of Calculation in Eyes with Against- and with-the-Rule Astigmatism

	enVista	EVO	p-value
Against-the-rule (n = 67)
Mean ± SD (D)	0.58 ± 0.43	0.59 ± 0.39	0.7673
Centroid ± SD (D)	0.27 ± 0.67 @ 175	0.18 ± 0.69 @ 095	x-component: p < 0.0001 y-component: p = 0.6405
With-the-rule (n = 38)
Mean ± SD (D)	0.73 ± 0.42	0.54 ± 0.37	0.0055
Centroid ± SD (D)	0.56 ± 0.64 @ 002	0.17 ± 0.65 @ 082	x-component: p = 0.0055 y-component: p = 0.6189
p-values
Means	0.08	0.55
Centroids	0.0061	0.596

Abbreviations: D, diopters; EVO, Emmetropia Verifying Optical toric IOL formula v2.0; SD, standard deviation.

Figure 3 Double angle plots of the residual astigmatism prediction error by method of calculation and sub-group. (A) enVista against-the-rule (ATR), (B) enVista with-the-rule (WTR), (C) EVO ATR and (D) EVO WTR.

Abbreviations: D, diopters; EVO, Emmetropia Verifying Optical toric IOL formula v2.0; red circle, 95% confidence ellipse of the centroid; blue circle, 95% confidence ellipse of the dataset.

Table 4 Residual Astigmatism Prediction Errors by Method of Calculation and Intraocular Lens Toricity

Intraocular Lens	enVista	EVO	p-value
MX60T125 (n = 79)
Mean ± SD (D)	0.63 ± 0.44	0.57 ± 0.39	0.1331
Centroid ± SD (D)	0.36 ± 0.50 @ 177	0.17 ± 0.47 @ 094	x-component: p < 0.0001 y-component: p = 0.1315
MX60T200 (n = 18)
Mean ± SD (D)	0.62 ± 0.46	0.57 ± 0.38	0.5689
Centroid ± SD (D)	0.40 ± 0.26 @ 002	0.16 ± 0.23 @ 086	x-component: p < 0.0001 y-component: p = 0.6215
MX60T275 (n = 12)
Mean ± SD (D)	0.63 ± 0.38	0.61 ± 0.36	0.8565
Centroid ± SD (D)	0.38 ± 0.20 @ 010	0.25 ± 0.19 @ 081	x-component: p < 0.0001 y-component: p = 0.0492
p-values
Means	0.9982	0.9442
Centroids	0.9942	0.9942

Abbreviations: D, diopters; EVO, Emmetropia Verifying Optical toric IOL formula v2.0.